Mike Johnson, a spokesman for the police department in Bellevue, Wash., told KOMO, ABC's Seattle, Wash., affiliate station, that they released the additional photos because they more accurately depict what the mother and child looked like on the day Sky disappeared.

She is shown standing alone in a store, wearing the same gray sweat suit she wore on Nov. 6 when she told police that she left Sky Metalwala in her stalled, unlocked car for an hour while she walked a mile to buy fuel at a gas station.

When Biryukova returned, the boy was gone, she told police, who also said that Biryukova has refused their request to interview her regarding her child's disappearance.

At least for now, authorities have opted against arresting Biryukova for not cooperating with an investigation that has included searching the areas around his home and the locale where she said the boy vanished.

Police said Friday that they've checked all but a dozen of the roughly 1,200 tips that residents called in about the case but none have panned out.